It so happens that one of my favourite colour combinations is green and gold. Something soft, yet rich erring on the sophisticated. Maybe it is something that captures that turn in to Autumn when gold leaves fall on to green grass.

Whatever it gives a rather tenuous segue in to the fact that this last month we had our next Green Tourism inspection. We get inspected by the Visit England tourist board people to check our quality is up to snuff, and they are sticklers for detail and cleanliness. With the Green Tourism crowd they also have an eye to quality but the real detail they dig in to are the fact and stats around our environmental and sustainable operation, something that also extends to social impact and fair trade. This a standard we have from the start cared most about and we were surprised and proud to get gold on first attempt - something we were told is pretty unusual.

But the trouble with hitting a high mark is the only way to go is down ... or at least (and hopefully) stay put. SO it is a vaguely anxious time, even though the people doing the assessment are very friendly, full of good advice and very professional. You don't realise you are actually being interrogated.

This time around the green Tourism people have launched a new tool to log all key utility usage ahead of the visit, and we duly complied. And it has proved very useful - partly because by way of a minor panic it helped us resolve on ongoing and nagging question. Namely - why do our guests use so much gas?

Being a bit of a nerd when it comes to all things technical, when the cottage was converted we were careful to ensure all main utilities were sub-metered. Water, Gas and electricity, including electricity imported and exported by the PV panels, is metered and I read and log these after every stay. As they say if you cannot measure something you cannot know what to improve on, and in particular what to focus on.

I checked and double checked the figures on several occasions before - they were always correct. The calculation to go from a gas meter reading to kWh and on to £, is remarkable complex and arcane. But the calculation is there for us to see on our main gas meter bill and from that I can calculate cottage use in my wonderful spreadsheet. Everything looked good.

But the Green Tourism tool prompted me one more time. And this time I did a test to run gas usage for 30 minutes only in the cottage, and took readings from both meters. Instead of them showing identical amounts, the cottage meter was showing 3 times the amount. what was going on?

Finally I twigged it. Older gas meters measure units that are imperial, and our cottage has a new meter which already reads in metric. The difference is - you guessed it - is a factor of 3. Problem solved, historic logs corrected, and our rating for energy use with Green Tourism hit excellent levels for what is still a solid walled old building, and not one of the super efficient Passivehaus type dwellings.

Anyway - that boring but nerdy story leads us to the good news that we got our Gold Award again. So as and when you come to Gorge View Cottage you will know it really is a very environmental stay.